Treatment of solvent refined oils with adsorbents



Paientcd Apr. 11, 1944 UNITED STATES an ler rric TREATMENT OF SOLVENTREFINE!) OILS WITH ADSORBENTS Thomas P. Simpson, John W. Payne, and?eter D. Valas, Woodbury, N. J., assignors to Socony- Vacuum OilCompany, Incorporated, New York, N. Y., a corporation oi New York NoDrawing. Application March 20, 1941, Serial No. 384,284

6 Claims. ('01. 196-447) V In the first method, the clay falls orcascades over to a method of treating solvent refined oils with v solidadsorbent materials 01' increased activity and useful life.

Practically all petroleum products require some refining to produce amarketable product. In former years the refining of heavy oils, such as,the lubricating oils almost universally comprised a sulfuric acidtreatment for removing undesirable components. Of late years aconsiderable amount of the sulfuric acid treating of lubricating oilshas been eliminated by the advent of solvent refining. In thesewell-known solvent refining processes, the solvents make preferentialselections of the desired components. However, whether the oils aresubjected to sulfuric acid treatment or to solvent refining or both, itis common practice to pass the oils through a further refining treatmentwherein they are contacted with solid adsorbent materials, such asclays. The clays serve principally to improve the color .of the oil, butmay also perform addi -tional refining actions. In the usual practicetoday the oil or the oil with added diluent is percolated throughgranules of the clay. Our present invention is concerned with thetreatment of oils which have been solvent refined as distinguished fromthe treatment of oils which have been only acid-treated.

In general three different methods are used for refining petroleum oilswith clays. These methods are the percolation process wherein liquid oilis percolated through granules of the clay, the contact process whereinliquid oil is contacted with finely pulverized clay and the vaporprocess wherein oil vapors are passed throughgranules of the clay.Usually the clays used in vapor processes are transferred to percolationprocesses after one use and the contact clays are usually discardedafter one use.

As may well be appreciated enormous quantities of clays are usedthroughout the petroleum industry. After the clays have refined acertain amount of oil, they become so contaminated with carbonaceousimpurities collected from the oil that they must be regenerated ordiscarded. Heretofore this regeneration has been eiiected principally bya chemical combustion which universally consists of burning off theimpurities.

In the past various methods have been used for carrying out the burningof granular spent clay. One of the first comprised spreading the clay onan open hearth and burning it. Today, there are three principal methodsin general use.

bafiles set at about a 45 angle through a fine countercurrent to gasesof combustion. In the second method, the clay is regenerated in a rotarykiln slightly inclined from the horizontal. In the third method, whichprobably is the most commonly used, multiple hearth burners areemployed. These multiple hearth furnaces or burners are substantiallythe same as used in the roasting of ore and are of either the Nichols-Herreshofi or Wedge type. In these burners the 'clay is slowly rabbledacross each hearth, dropping from one to another until the bottom hearthis reached. In all of these conventionally used methods, there is aprogressive degradation in the efficiency of the clay with each burning,and finally the clay must be discarded to waste-since it is no longercapable of being regenerated sufficiently to warrant further treatment.

The two co-pending applications Serial Number 210,150, filed May 26,1938, and Serial Number 270,943, filed April 29, 1939, of John W. Payne,disclose and claim two other methods adapted iorregenerating clay.

Since clays which have had a different number of burnings by the presentconventional processes have different efilciencies, they are keptseparate and separately classified. In some of the larger refineries,extensive inventories and bin facilities are required in order tomaintain the clays according to their classification or eificiency. Notonly do the large inventories of clay, bin facilities, etc, mean addedexpense, but quite obviously the successive degradation in efficiency,and the corresponding requirement of more clay increases the expense.

Most important amongst the disadvantages of the commonly used clayregeneration methods, however, is the fact the clay can only beregenerated a very limited number of times before its efficiency is solow that it does not pay to regenerate it, at which time the clay isthrown away to waste. In general, granular petroleum filter clays areonly regenerated seven or eight times, and practically never more thanten or fifteen times at which time their efficiency is reduced to aboutof the original, and they are thrown away. As stated above, the finelypulverized con tact clays, e. g., 200 mesh or finer, are usually neverregenerated. 1

In order to further stress the tremendous importance of the probleminvolved it might be pointed out that over the United States there areroughly 5,000 tons of clay regenerated each day with the attendantdegradation in eificiency accepted by the art. Furthermore, each yearthe petroleum industry purchases about 225,000 tons of new fullers earthalone, representing an expense of over four million dollars, anddiscards to waste roughly 200,000 tons of clay that is considered toospent to warrant regeneration.

It is a well-known fact that every heavy oil refinery in the country haslarge dumps of spent clays that have been thrown away to complete waste.In some cases, this waste clay is left as a dump, and in other cases, itis used for filling in low land, sold for fertilizer, etc. However, inall cases, there is this enormous discarding of spent clays. Such wasteis accepted as a necessary evil of the process.

There have been a few suggestions from time to time in other fields thatclays might be regenerated to higher efficiency. Likewise, in thepetroleum industry, it has been suggested that a particular form of clayunder very special conditions might be regenerated to higher efiiciency.However, the fact other methods have not been taken up by the petroleumindustry is believed conclusive that other known regeneration processesthan those now used are not feasible for successive losses in efilciencyas well as other attending disadvantages. Certainly, it cannot bemaintained that one of the countrys largest industries would go on yearafter year suffering the above-mentioned wastes and disadvantages, if aremedy therefor was obvious.

It is an object of our invention to provide an improved method oftreating solvent refined petroleum oils with solid adsorbent materialsby using adsorbents possessing higher refining activity for solventrefined oils.

Another object is to provide a method of treating solvent refinedpetroleum oils with adsorbents, such as, .clays and the like, whereinthe adsorbents have a greater refining activity than in theirconventionally used fresh state, and wherein said adsorbents may beindefinitely regenerated to high efficiency.

A further object is to provide a commercially feasible method oftreating solvent refined petroleum oils with adsorbent materials, suchas, clays, and the like, which have been reclaimed from discardedpetroleum filter materials.

Still another object is to provide a method of treating solvent refinedpetroleum oils with adsorbent materials, such as, clays, and the like,wherein the adsorbents do not suffer successive degradation ineificiency with successive. regenerations.

The present invention comprises subjecting finely divided porousmaterials which have carbonaceous matter associated therewith to acarbonizing treatment whereby the carbonaceous matter is converted to adeposit of activated carbon on the porous material, and then treatingsolvent refined petroleum oils with the carbonized material. While itmay be found desirable at each activation treatment or at intermittenttreatments to burn off part of the carbonaceous matter or carbonassociated with the clay or other porous material, the essential featureis that at each treatment at least a sufficient portion of thecarbonaceous product associated with the clay is carbonized on the clayto a highly active carbon deposit, to give the clay an enhanced refiningactivity. We recommend that the activated carbon layer comprises atleast about 2% by weight of the adsorbent.

We disclose in our co-pending application Serial Number 275,672, filedMay 25, 1939, the advantages of carbonizing petroleum refining clays ingeneral, and point out therein that contrary to the, conventionalregeneration processes of today which regard the carbonaceous impuritiesas a complete evil Which clogs the porous structure of the adsorbent,and which must be burned off, our carbonizing process makes use of atleast a portion of this carbonaceous impurity by converting it to anactivated carbon deposite on the clay. In our co-pending case S. N.275,673, we claim the invention based on the discovery that adsorbentshaving petroleum matter carbonized thereon have a refining activity forsolvent. refined oils that is far superior to even its own activity forother oils. The present invention is generic to this latter process, andis based on the discovery that carbonaceous matter in general, whethermineral, vegetable, or animal, can be carbonized onto adsorbents, andthe carbonized adsorbents used for refining solvent refined oils withthe advantages set forth in application S. N. 275,673.

It must be admitted, of course, that activated carbon is a knownadsorbent material. However, as pointed out hereinabove, despite thelong recognized disadvantages and wastes of the conventional clayregeneration methods, the long desire for improvement, and the manyattempts to improve, it has never occurred to the petroleum industrythat the petroleum oil impurities deposited on their clay adsorbents, orother carbonaceous matter placed thereon, could be successfully andfeasibly converted to activated carbon which would give the clay even asefficient activity as it would have by completely burning off theimpurities, and it certainly has never occurred to the art that suchcarbonized clays had far greater activity for solvent refined oils thanfor acidtreated oils. Accordingly, the art goes on today regeneratingthe clays, such as, used in the percolation methods, in the manner setforth above. resigning itself to the decreased efliciencies, anddiscarding to waste enormous quantities annually. The finely pulverizedclays used in contact processes, although not so commonly used, are asstated above generally discarded to waste after the first use with noattempt to regenerate since a process considered feasible for theirregeneration has not been suggested. Therefore, the present invention isparticularly feasible for contact clays since they may be contacted withoil, carbonized, then the above cycle repeated many times, and thereby acontact adsorbent is afformed, having substantially greater eflieiencythan the uncarbonized clay. Moreover, it is to be understood, that byour process contact clays may be contacted with carbonaceous matter,carbonized, and then the above cycle repeated several times.

The method of activating or regenerating clay for our processnecessitates but little change in the present burning methods and meansfor regenerating clays. While other methods might be devised whichincorporate the principles of our invention, it is preferred to operatein a manner closely analogous to present burning method, thus increasingthe commercial acceptability of the process.

Accordingly, the activation or regeneration may be carried out byheating, for instance, spent petroleum filter clays under the well-knownclay burning conditions of time, temperature, etc., but with control ofthe atmosphere contacting the clay in such manner that the regeneratedclay carries an activated carbon deposit rather than having all theimpurities burned off. The carbonized clays thus produced are used inthe conventional methods for treating solvent refined oils with clays.

It has been found that the temperature of our carbonizing regeneratingor activating process may be varied over a considerably wider range thanis desirable in the clay burning regeneration methods now being used.Thus in our regenerating process the temperatures required fordestructive distillation of the adsorbed petroleum products may varyfrom that necessary to provide incipient distillation up to that whichwill be damaging to the clay under the circumstances. In theconventional regenerating methods wherein the impurities are burned fromthe clay an extremely close temperature control should be maintained asotherwise inefiicient regeneration or damage to the clay results. Thetemperature for clay burning should preferably be maintainedsubstantially within the range of 950-1150 F. However, in the presentprocess it has been found that the carbonization regeneration may beefrected, for instance, within the range of about 900-1500 F. with equalsuccess. This is of itself a distinct advantage since there is lesschance of damaging the clay. Ihe optimum time of heating varies from afew seconds at 1500' F. to several minutes at 1000 F.

The important feature in activating or regenerating by the presentprocess is proper control of the atmosphere in the regenerating oractivating zone. The essential feature is to sufficiently restrict theamount of air or other carbon oxidizing gas in the zone that completecombustion or oxidation of the petroleum products will not cur. It hasbeen found that carbonization takes place both in the complete absenceof air or other carbon oxidizing gas, and also in the presence oflimited amounts of air provided the quantities are insufiicient tooxidize the activated carbon from the clay. Thus in carrying out thecarbonization, the heating zone may be completely sealed and no airadmitted, or a limited amount of air may be admitted with or withoutother inert gases. It has also been foundthat, if desired, steam may beadmitted to the carbonizing zone. The presence of steam facilitatestheremoval of hydrocarbon vapors and reduces the rate of carbon build-upon the clay, For some oils, it appears carbonizing in the presence ofsteam gives slightly better results, however, in

general, reactivation is approximately the same for all the abovecarbonizing methods.

of John W. Payne wherein the clay is passed through the regeneratingzone in close proximity to a liquid heat transfer medium. Theseapparatuses have several construction and operating ad vantages overother known regenerating kilns. In regenerating clays by burning, as isnow commonly done in the art, an extremely close temperature controlshould be maintained, and for such regenerations the above-mentionedPayne apparatuses are highly advantageous on this point alone.Furthermore, the apparatus disclosed inSerial Number 270,942 iswell-suited for regenerating the finely divided contact clays as well asthe granular clays, the clays being carried through the apparatussuspended in a gaseous medium. However, as mentioned hereinabove, theclose temperature control of burning regenerations is not necessary inthe present carbonizing process. Accordingly insofar as the degree ofreactivation is concerned the present process may be carried out inother apparatuses, such as, the ballled vertcal flue, rotary kiln, ormultiple hearth kilns now in common use in the industry with equalsuccess, the clays being passed through these kilns in the same mannerin which they are under burning methods, it being understood, of course,that in any apparatus used, appropriate provision must be made forcontrolling the amount of air or other combustion supporting gasadmitted to the carbonizing zone. It is believed, however, that in anycommercial set-up, it will be found desirable to do a certain amount ofburning as well as carbonizing. Accordingly, it is preferable to employone of the Payne apparatuses, as then the one apparatus may be used forboth the burning and the carbonizing. Otherwise, if it is desired toobtain the advantages in burning that may be given by the Payneapparatuses, separate kilns must be used for the carbonizing and theburning.

A considerable amount of research, experimenting and testing has beendone in developing and establishing the present invention. In order toclearly establish the surprising improvements which the presentinvention makes over the present conventional regeneration methods, asubstantial amount of data will be set forth herein. All of the activitytests are tests of the decolorizing efficiency of the clay by the,percolation method, and the values are based on fresh clay as being100%. The number of the clay indicates the number of times, it has beenregenerated (by conventional burning or the present carbonizing asindicated after the number). Variolls petroleum stocks were used in thetests, and they are as follows:

In practice we prefer to carry out our regenerating process inapparatuses, such as, disclosed in the two co-pending applicationsSerial Number 270,942, and Serial Number 279,008, filed It will berecalled that one of the principal objects of the present invention wasthe regeneration of clay to a higher activity than is obtainable bypresent methods in common use. That April 29, 1939, and June 14, 1939,respectively, such object has been attained to a high degree 4-2,340,127 by the present invention can be seen clearly from carbonizedclay showed marked improvement the following data: I over thecorresponding burned clay. It is need- T LE I less to point out thecommercial advantage of Comparative yields from burned and carbonizedsuch increased activity- It m be mud that on clay some of these oils,the activity of the carbonized clay goes even above 200%. Furthermorethat per cent percolation clays which have been burned times and upon lf fg fgg g'iz g another burning regeneration have an efficiency 10around 50, at which time, they, would usually Swck 1 Multiple bediscarded to waste, may be regenerated by I 352; C g ze our carbonizingprocess and have their efliciency clay go up above 200%.

It was pointed out in our co-pending appli- A Fresh burned 100 100 5cation Serial Number 275,672, filed May 25, 1939, gg-g that there is adistinct advantage in the use of B Fresh burned 100 100 our carbonizedclays for treating petroleum fig gl gg oils. It has now been found thatfor unknown 0 Fresh burned-... 100 100 reasons carbonized clays displayunusually high- 9 Z: activities with respect to solvent refined oils,and

gg particularly for oils which have beensolvent re- 100 100 fined by theDuo-S01 process, the activity for 3% these oils far surpassing eventheir own activities No.3 so 130 on acid treated oils. This importantdiscovery 25 is clearly demonstrated by the following data:

Tenn: II

Solvent refined oils i t d c s 1 u i c dt s 1 u i fii percoae 0 cu onpercoae 0 on on perooae to Clay method of reactivation Lov. (A) Lo (A)Lev. straight straight straight Car No. 1 fresh clay 173 No. 2 freshclay 183 N0. 3 fresh clay 183 No 4fresh clay. 183 N0 5 fresh clay. 210No Gfresh clay 206 No 7fresh ela 206 No 8 fresh cla No 9 fresh clay 286No. 10 fresh clay 237 No 11 fresh clay 286 No 13 fresh clay. 173 No 14fresh clay. 194 N o. 15 fresh clay...

Average--. 206

Acid treated stocks Stock F, Stock 686,' Stock E, percolated percolatedpercolated Solution to 6 Lov. to 1.2 Lov. to Lov. (A) straight straightstraight Carbonlzation of fresh clay No.

Carbonlzation of fresh clay No. Carbonlzatlon of fresh clay N o.Carbonizatlon of fresh clay N0. Carbonizatlon of fresh clay No. 5Carbonization of fresh clay N o. Carbonlzation of fresh clay N0.Carbonization of fresh clay No. 8 Carbonlzation of.fresh clay N0. 9Carbonlzation of fresh clay N 0.

Average 1 Initial Color 105 Lovibond (VW cell).

3 Initial Color 120 Lovibond (54" cell).

1 Initial Color 95 Lovlbond (34" cell).

4 Initial Color 15 Lovibond (54" cell).

5 Initial Color 316 Lovibond (54 cell).

Initial Color 750 Lovibond 04 cell).

(A) Solution consists of 50% (vol.) 011 and 50% ("01.) of naphtha.Yields are based on reduced oil.

The tremendous improvement and advance- Thus, while our carbonized claysmay be used merit of the art by the present process is apparwithadvantage on any oils, it is apparent from ent from the table. With allthe oils treated, the the above data that such clays have a tremen- 7 to10 regenerations. From the above table, it is seen that at 7 to 10regenerations by our process the efiiciency of the clay is still at avery high level, and that the eiilciency stays at the high level uponfurther regenerations. clays could be regenerated forever by ourprocess, however, by present methods and means of regeneration there isabout a 2% mechanical loss of clay from handling with each regeneration.Therefore, the clay is lost through handling before it reaches a pointat which regeneration is not feasible. As the loss is about 2% perregeneration, this would mean the clay could be regenerated in practiceabout 50 times.

One of the most surprising and important features of the presentinvention is the fact that clays whichhave been regenerated byconventional burning methods until their efficiency is so low it nolonger pays to regenerate them, i. e., they have been burned about 10times and their efllciency is around 50 or 60, may now be sub jected toour carbonizing treatment and their efliciency becomes greater than theoriginal fresh clay. More surprising still is the fact it is possible toreclaim these burned clays that have been thrown away. For instance, itis possible to bring in discarded clays oil the dumps at the refinerywhich, as explained above, have been thrown'away because of their lowefllciency and subject these discarded clays to our carbonizing processand bring their efllciency or activity up to a value which is greaterthan that possessed by the original fresh clay. In the case of discardedcontact clay, it has also been found feasible to convert same togranular clay by extrusion, e. g., forming 30/60 mesh granules,carbonize these synthetic? granules and use them in percolationtreatments of solvent refined oils. The following data illustrates thetype results Theoretically that may be obtained with reclaimed discardedPetroleum filter clays:

Tenn: III Clay-Method o! reactivation Stock A Stock 13 percoiatedpercoiated to 55 Loy. to Lov.

straight straight (urbanization No. l of No. 10 refinery clay, 164(urbanization N o. 2 of No. 10 refinery clay. 149 248 (arbonization No.3 of No. 10 refinery clay. 129 1 (arbonization No. 4 of N 0. l0 refineryclay. 131 i larbonization No. 5 of No. 10 refinery clay. 125 124(urbanization No. 6 of No. 10 refinery clay. 139 128 Carbonization No. 7ol N0. 10 refinery clay. 149 194 Carbonization No. 80f No. 10 refineryclay. 163 230 Carbonization No.9 of N o. 10 refinery clay. 1,63 239Carbonization N o. 10 of No. 10 refinery clay. 159

Average 145 In order to demonstrate clearly that the carbonaceous matterwhich is carbonized on the adsorbents need not be petroleum, exemplarydata are given in Table IV below, showing results wherein typicalcarbonaceous materials from the animal and vegetable kingdoms werecarbonized on the adsorbents prior to their use for decolorizing a DuoSol solvent refined Mid-Continent residual stock.

TABLE IV b Ads b t d l i z w.car on or en eooor Adsorbent on addensitying efli sorbent ciency 1 Fresh burned clay (i 496 100 2 do 0 V .499 1003 Carbonized clay from lard impregnation 2. 38 533 203 4 Same as No. 32, 38 .525 209 5 Carbonized clay from olive oil impregnation... 2. 25532 199 6 Same as No. 5 2.25 .533 200 7 Carbonized clay irorn inolassesimpregnation.. 9. 15 586 188 8 Same as No.7 9.15 .585 188 Thetremendously important commercial aspects of all the features of ourinvention should be readily apparent from the foregoing data. It isobvious from the data that very substantial savings may be made overpresent processes.

Since it may not be apparent from the data, it might be well to statethat carbonized or burned clays which hav been used for refining acidtreated oils may b subjected to a carbonizing treatment, and it is thenused for refining solvent refined oils, and it is found that; theiractivity for the solvent refined oils is of the extremely high nature ofthe clays shown in the tables.

The physical characteristics and oxidation stability of oils percolatedthrough our carbonized clays are approximately the same as those of oilspercolated to the same blend color through conventionally burned claysas is shown by Table V.

TABLE V Properties of oils percolated through carbonized and plantburned clays TABLE if-(Continued) Color 5. U V.@

Stock Type of clay V. I.

Lovlbond Story 100 F 210' 1'.

M" cell) (1" cell) 8 A No. 10 plant clay after 2 carbonlzations 63 50 AAfter 4 carbonizatious 56 50 678 67. 2 96 A No 7-10 plant clay after 1carbonlzatiom- 67 57 671 66. 9 95. 4 11 A Fresh clay after 1 car.without steam- 57 69 12 A Fresh clay after 4 car. without steam 56 54676 67. 8 96. 1 13 B Fresh burned clay 72 87 1, 049 90. 6 95. 6 l4 B N0. 5-10 plant burned clay 73 91 1,042 90. 4 95. 8 15 B Fr. clay burnedafter 16 carbonizations 75 81 973 87. 1 95. 6 16 B Fr. clay after 2carbon 76 91 1,058 91. 6 96. 6 17 B Fr. clay after 10 carbon 76 93 1,063 91. 4 95. 6 18 B No. b-iO plant clay after 1 carbonization 76 79 1,002 88.4 95. l 19 B No. 10 plant clay after 2 carbonizations 76 85 l,064 91. 2 95. 3 20 B After 4 carbonizations 75 81 998 88. 2 95. 8 21 0Fresh burned clay 12. 5 8.0 22 0 Clay burned after 6 carbonlzatlons.-12. 5 8.0 23 0 Fr. clay after 5 carbon 16. 0 l3. 5 24 0 Fr. clay after 9carbon 12. 6 9.0

In addition to the advantages set forth hereinabove, it has been foundthat certain other advantages are obtained by using our carbonized claysin the refining of solvent refined petroleum oils. It has been foundthat when 0. Duo Sol treated oil is percolated through burned clay, thecolor of the filter stream becomes darker by relatively constant colorincrements and is soon darker than the charge oil. Percolation of DuoSol treated oil through our carbonized clay, however, results in streamcolors which darken by progressively smaller color increments, thusresulting in larger filter yields. The stream colors are approximatelythe same for percolation of acid-treated oils through either burned clayor carbonized clay. (The percolation yields 0! Duo Sol refined oils areconsiderably higher for straight percolation than for solutionpercolation, but the percolation yield of acid treated oils isapproximately the same.) The color of the wash oil from carbonized clayis about the same as that of normally burned clay.

A further advantage of the present process results from a more efiicientactivation or regeneration that is possible. Because of this moreefiicient regeneration, smaller inventories of clay are required andconsequently less capital investment. Moreover, the extensiveclassifications and bin facilities required by present day conventionalmethods of regeneration may be eliminated. Under the present process,the clay need only be separated into two classes, that is, fresh clayand revivified or carbonized clay.

While the invention has been described hereinbefore, principally withrespect to regeneration of spent clays, the invention may be made use ofto increase the activity of fresh clay. Thus, fresh clay may be dippedor otherwise coated with a suitable petroleum oil, and then subjected toour carbonizing process, thereby giving it an activity which is greaterthan its original activity. It is in such operations that the use ofcarbonaceous materials other than petroleum is more important.

The invention has been described in detail with respect to treatment ofpetroleum refining clays. While clays, and particularly fullers earth,are by far the most commonly used solid adsorbent means for refiningpetroleum today, other solid adsorbent materials, such as, bauxite,silica, gel, etc., are used to a limited extent in place of clays. It isunderstood that the present invention is applicable to these other solidad- 15 sorbent refining materials that may be used in place of clays,and, in fact, any finely divided porous material which does not have adeleterious chemical action of its own may be used as the carrier forthe activated carbon deposit.

We claim:

1. In the method of treating oils which have been partially refined bysubjection to the action of preferential solvents for the removal ofimpurities and the subsequent separation of the dissolved impuritiesfrom the remaining stock, the steps which comprise contacting saidremaining stock with a porous, solid, inorganic adsorbent, havingthereon a deposit of carbonaceous material added to the adsorbent andless than all of which has been burned off to leave a residual depositof activated carbon.

'2. The method of increasing the efllciency of a decolorizing operationfor oils which have been partially refined by subjection to the actionof preferential solvents for the removal of impurities, subsequentseparation of the dissolved impurities from the remaining stock andtreatment of the remaining stock with a solid, inorganic adsorbent inparticle form, the improvement which comprises impregnating theparticles of adsorbent with carbonaceous material, carbonizing saidcarbonaceous material to form an active carbon deposit on said particlesof adsorbent before contacting with said remaining stock, whereby theefilciency of the carbonized adsorbent for solvent refined oils issubstantially greater than the efiiciency of the adsorbent in its freshstate.

3. The method of claim 2 wherein the activated carbon deposit on theinorganic solid adsorbent is equal in amount to at least 2 per cent byweight of the particles.

4. The method of claim 2 wherein the carbonaceous material is selectedfrom the mineral kingdom.

5. The method of claim 2 wherein the carbonaceous material is selectedfrom the vegetable kingdom.

6. The method of claim 2 wherein the carbonaceous material is selectedfrom the animal kingdom.

THOMAS P. SIMPSON. JDHN W. PAYNE. PETER D. VALAS.

